Feedstock Flexibility a key to project success

Fluidized bed technology supplier Energy Products of Idaho first entered the biomass industry in Coeur d'Alene, Idaho, when the forest products industry in that area was booming.

That was more than three decades ago, says EPI’s Business Development Manager Jim Starkey, and much has changed since then. “People often ask how we ended up in Coeur d'Alene, and it was because it had a very thriving forest products industry at the time—over a dozen mills were in the area then, though there is only one operating mill now,” he said.

According to Starkey, these mills were pile-burning wood waste and generating a lot of emissions, besides letting useful energy go to waste. “We formed there as a way to take some of that wood waste and turn it into useable energy,” he said. “That was over 35 years ago, and we’ve really branched out.”

During break-out session Everything but the Kitchen Sink: Multi-Feedstock Capable Technologies, at BBI International’s Pacific West Biomass Conference & Trade Show, Starkey discussed the company’s fluidized bed gasification technology and experiences with it over the years.

He and three other industry experts emphasized the importance of employing biomass power technologies that have the ability to efficiently handle/process multiple biomass fuel sources, some of which are proven, well-established technologies and others that are newer but promising.

Starkey said EPI’s system can handle more than 250 biomass fuels, which is a huge advantage. “One problem with gasification is that fuels typically have to have a high Btu value and low moisture content,” he said. “If the moisture content is too high and the Btu value too low, your bed will cool and you’re no longer gasifying the material. By doing combustion in a separate vapor space like we do, you’ll get radiated heat down into the bed area, so you’re keeping it hot all the time. We can gasify fuels that have 3,000 to 4,000 Btu per pound and 60 percent moisture content; fuels that other systems typically can’t gasify.”

EPI has installed more than100 systems in North America and Europe, most of which are run on multiple fuels, according to Starkey. “Typically there is one main opportunity fuel that is primary fuel, but we have some facilities in California that have been operating for more than 20 years that use from 50 to 70 fuels each year. These are located in agricultural valleys and use ag waste. We can use ag waste in our systems, because we keep our temperatures very low—typically for other systems, since ag waste has a lot of alkaline materials, it will cause slagging issues.”

Thermal oxidizers like EPI’s are the way of the future, according to following presenter Edan Prabu. He discussed FlexEnergy’s FlexPowerstation, which combines a modified gas turbine with an adaptation of a proprietary thermal oxidizer. “Our mission is to eliminate emissions in a wide range of fuels, with a focus on problematic weak gases,” he said.

In short, the FlexPowerstation is a modular system that converts methane sources into electricity with very low emissions, and has the ability to cleanly and efficiently consume the widest range of methane gases from 100 percent down to 5 percent or lower, according to Prabu.

Operations that produce low Btu gas, such as landfills, coal mines and digester plants currently flare or vent this methane gas into the atmosphere. “Methane is going up into the atmosphere in such large quantities it’s embarrassing,” Prabu said. “But [methane] is a very sweet word to us.”

He said the FlexPower Station technology enables the utilization of a whole host of waste gases that today are a considerable source of greenhouse gas emissions. How? “In a simple description, we take the thermal oxidizer and pressurize it, but mix the fuel and the air prior to entering the thermal oxidizer,” he said. “There are a few other magical tricks we do inside it, but it works,” he said.

The company has a couple of systems in operation, including one in San Diego.

Other panelists following Starkey and Prabu included vice president of Harris Group Inc. John Logsdon, who provided an overview of several biomass power technologies including torrefaction, pyrolysis, gasification and combustion, and PreProcess Inc. senior engineer and cofounder Christina Borgese, who discussed conventional multi-feedstock biorefining.

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